Hydraulic press system



March 17, 1936. T. F, sTAcY HYDRAULIC PRESS SYSTEM Filed June 9; 1933@MPL W www] A TTOIQ/VE-V.

Patented Mar. 17, 1936 UNITED STATES 2,034,157 HYDRAULIC PRESS SYSTEMThomas F. Stacy, Piqua, Ohio, assignor to The French Oil Mill MachineryCo., Piqua, Ohio Application June 9, 193s, seriaiNo. 675,069

19 Claims.

This invention relates to hydraulic press systems, .and particularly tothe operation of single acting hydraulic presses in which the platen isforcibly moved in one direction by hydraulic means and returned by othermeans, such as gravity, to starting position.

An object of the invention is to provide improved means for operating asingle acting press, which will cause a rapid movement of the platen asit closes against the work and then a smaller movement under substantialpressure; which may be operated by means of a relatively small pump;with which hydraulic valves under pressure are not required; with whichthe operation of the 1,. press, may be controlled solely by the reversalof the pump; which will require a minimum of valve equipment; which willbe compact and simple in construction; which will have a lowmanufacturing vand operating cost; and which will require a minimum ofattention during use.

Another object of the invention is to provide improved means foroperating a single acting press which will be semi-automatic in action;with which the press will be opened automatically a selected interval oftime after the pressing stroke has been initiated; and with which therise of pressure above a selected maximum o said platen will beprevented. p

Various other objects and advantages will be apparent from the followingdescription of an embodiment of the invention, and the novel featureswill be particularly pointed out hereinafter in connection with theappended claims.

In the accompanying drawing:

Fig. l is a side elevation, partly in section, of a simplified type ofsingle acting, hydraulic press and a controlling and operating systemtherefor, constructed in accordance with this invention; and

Fig. 2 is a sectional elevation of one type of timing element which maybeemployed in suchl controlling system.

In the illustrated embodimentof the invention, the single acting pressincludes a frame I0 which guides a platen II in a vertical directiontoward and from a relatively xed pressure head I2. of a piston I3reciprocating in a cylinder |4 and together with the cylinder forming amain ram, and also by one or more smaller pistons |5, two being shown byway of example, reciprocating in cylinders I6, each piston. I5 and itscylinder I5 together forming an auxiliary ram for urging the platen IIupwardly in the same direction as that produced by the main ram. Areversiabutments 35 on the rod 3|, and the rod 3| The platen I I iselevated or raised by means ble, variable delivery pump I1 is connectedat one side by a pipe I8 tofeach cylinder I6, and at its other side bypipes I9 and 20 to a reservoir or suitable source 2| of operating iluid.The pipe from the reservoir 2| is connected to a chamber 22 of a freecheck valve 23. The movable valve element 24 of this free check valve isurged toward a cooperating Iseat 25 by a spring 26.

The valve seat 25 separates the chamber,22 from another chamber 21 sothat communication between the chambers 22 and 21 is prevented when thevalve element 24 is engaged with its seat. The valve element 24 opensfreely against the action of its spring 2 6 to pass uid from the pipe 204through the valve' seat into the chamber 21, and closes automaticallyto prevent reverse flow. A pipe 28 connects the chamber 21 to thecylinder I4 of themain ram, from which it will be observed thatoperating 20 fluid from the reservoir 2| may pass freely through thepipe 20 to the chamber 22, thence through the valve seat and into thechamber 21, and thence to the ram cylinder I4, but reverse flow isautomatically prevented by the closing of the valve element 24.

The delivery of the pump I1 may be reversed in any suitable manner, butin the illustrated example, it is accomplished by a control element 29which is pivoted at 30 and operated by a 30 rod 3|. A small ram 32 isconnected by a pipe 33 to the pipe I8 which delivers fluid from thepumps to the cylinders I6. The ram 32 is connected to the element 29 toforce it into neutral delivery position automatically whenever the 35pressure in the pipe |8 reaches a predetermined maximum, which is thepressure required to overcome the spring 34. The spring 34 is compressedbetween the element 29 and adjustable passes slidingly through theelement 29 and carries a head 3B on its free end. The ram 32 can,therefore, shift the element 29 into a neutral delivery position againstthe action of the spring 34 without movement of the rod 3|. Pumps of thereversible, variable delivery typey are well known in the art and havebeen described only briefly by way of example, but it will be understood4that other pumps of this general type may also be employed instead ofthat illustrated and described herein.

A pressure operated vcheck vvalve 31 is connected by a pipe 38 to thepipe 28, and is oonnected by a pipe 39 to the pipe I8 which leadsdirectly to the auxiliary cylinders I6. This valve 31 includes a valveelement 40 which is urged into closed position by a weighted arm 4| toprevent ilow of fluid from the pipe 38 through the valve to the pipe 39,but opening to pass fluid from the pipe 39 to the pipe 38 wheneverpressure of fluid in the pipe 39 is sufllcient to lift the valve element40 from its seat against the pressure exerted on the valve element bythe weighted arm 4I. The pipes 38 and 39, of course, open into the valveon opposite sides of the valve seat 42 which is engaged'by the valveelement 49.

A freely operating check valve 43 is connected at one side by a pipe 44to the pipe 28, and at its 'other side by a pipe 45 to the pipe I8 whichconnects the pump to the cylinders I6. The pipes 44 and 45 open into thechamber of the valve 43 on opposite sides of Kthe seat 46 thereof, andthe valve element 41 reciprocates toward and from the seat 46 so as tomove away from the seat and pass fluid from the pipe 44 to the pipe 45,but closing automatically to prevent reverse ow from the pipe to thepipe 44.

In the operation of the press system by the means just described, let itbe assumed that the platen is in its retracted or lower position, andthat the pump control rod 3| is in the position shown in the drawing inwhich the pump is delivering fluid under pressure into the pipe I9 andwithdrawing it from the pipe I8. The fluid delivered through the pipe I9passes into the pipe 20, thence through the valve 23, during which itforces open the valve element 24, thence through the pipes 28 and 44,through the free check valve 43, thence through pipe 45 into pipe I8 andback into the pump. While the pump is so operating, the fluid handledthereby will circulate idly through the path just described, and nomaterial pressure willbe exerted on any of the rams attached to theplaten. At this time the reservoir 2| is acting mainly as an expansiontank for the operating fluid.

Let it be assumed that an operation of the press is desired. Thisoperation is initiated by a movement of the pump control rod 3|, to theleft in the drawing, which causes a reversal in the delivery of thepump. The pump will now withdraw fluid from the pipe I9 and deliver itunder pressure to the pipe I8. Immediately that iluid is withdrawn fromthe pipe I9, the valve element 24 may close and the pump 'will besupplied with operating fluid reaching the pipe I9 through the pipe 20from the reservoir 2|. 'Ihe uid delivered by the pump will pass throughthe pipe I8 into the cylinders I6 of the auxiliary rams, and will exertpressure on the pistons I5 of those rams tending to urge the platen IIupwardly. At this time, uid can not pass from pipe I8 through the pipe45 and the valve 43, because the valve 43 automatically closes toprevent this reverse flow.

At the same time the valve 31 prevents movement of the fluid from thepipe I8 through the pipe 39 and the valve 31 to the pipe 28 until thepressure in the pipe I 8 has increased to an extent suicient to raisethe valve element 48 against the pressure exerted thereon by theweighted arm 4I. As the pump continues to operate in this direction, thepressure of fluid delivered by the pump is effective solely on thepistons I5 of the auxiliary rams, and forces the platen I I upwardly ata rapid rate until it engages, or is closed against, the work.

As the platen |I moves upwardly under the pressure from the auxiliaryrams, operating iluid will enter the main cylinder I4 from the reservoiror source 2| by passing through the pipe 2G, the valve 23, and pipe 28,the suction created in the cylinder I4 by the elevation of the piston I3draw-- ingvthe fluid from the pipe 2D through the free check valve 23,and through the 'pipe 28. The filling of the cylinder I4 by theoperating fluid, directly from the reservoir, requires little power andis eifected by the atmospheric air pressure on the fluid in thereservoir 2|.

When the pressure on the auxiliary cylinder I6 increases to a selectedpressure suilicient to lift the valve element 49of the pressure operatedcheck valve 31, the fluid then delivered by the pump will not only passto the cylinder I6 but some will also pass through the pipe 39, thevalve 31 and pipe 38, to the pipe 28, and thence to the main cylinder I4so that the pressure in' the main cylinder is then equal to the pressurein the cylinders I6 as the pumpcontinues to increase the pressure. Allthese rams will then be operating on the platen to force it upwardly andcause it to perform its usual work, but as soon as the fluid began toflow through the pipe 39 and the pressure operated check valve 31, someof it started to flow reversely through the free check Valve 23 backinto the intake side of the pump, but the valve element 24 closedautomatically at the start of this flow through valve 23, and preventeda continuance of flow backwardly through the valve 23 to the pump.

The pressure of fluid delivered by the pump to the three rams continuesto increase and when it reaches a predetermined maximum, the small pumpram 32 forces the control element 29 into substantially neutral deliveryposition in which only sufficient fluid is delivered by the pump intothe pipe I8 to provide for `leakage and maintain the selected pressureon the three rams. This pressure will be maintained on the rams attachedto the platen indefinitely until the pump control rod 3| is operated toreverse the pump.

When the pressing operation has been completed and one desiresv to causea return of the platen to its lower or retracted position, the pumpcontrol rod 3| is operated to the right, in the drawing, so as to movethe control element 29 in a direction to reverse the delivery of thepump. When this occurs, the pump will draw fluid from the pipe I8 anddeliver it `into the pipe I9. Since the pipe I8 is connected to thecylinders I6, the pressure on those cylinders will rapidly decrease andthe uid under pressure in the main cylinder I4 will pass through thepipes 28 and 44, the free check valve 43, and pipe 45 into the pipe I3which is now connected to the intake side of the pump. The pump thusdraws iluid from all cylinders and rapidly lowers the pressure therein.The fluidl delivered by the pump through the pipe I9 passes through thepipe 29 into the reservoir 2| where it is stored for a new operation.

As the operating fluid is withdrawn from the rams, the platen II willsettle o r lower itself by gravity to prepare for a'new pressingoperation. If the pump I1 is of small capacity, the pumping of all thefluid from the three rams would require considerable time and power,which would retard the opening movement of the platen. In view of this,I provide means for forcibly opening the valve element 24 as soon aspossible, and when that occurs, the operating fluid displaced by themain ram, instead of passing through the free check valve 43 to the pumpor delivery reservoir, may now pass through the pipe 28 and the valve 23into the pipe 2U and thence directly back to the reservoir 2| withoutbeing handled by the pump. The platen then may lower as rapidly as theoperating uid is withdrawn from the relatively small cylinders |6through the action of the pump.

The valve element 24 is forced into open pos tion, against the action ofits spring 26, by an operating rod 48 which extends into the valvehousing and into a position to engage and operate the valve 24. Sincethe valve control rod 48 should be operated to force valve element 24into open position only while .the pump is being oper- Ameans by whichthis concurrent operation of the valve element 48 and the pump rod 3|may be obtained.

For this purpose, the valve rod 48 extends into a cylinder 49 and withinthe cylinder 49 carries a reciprocating piston 58. The cylinder 49, atone side of the piston 50, is connected by a pipe 5| to a port 52 of avalve box 53, and the portion of the cylinder 49 at the other side ofthe piston 50 is connected by a pipe 54 toa port 55 also opening intothe chamber ofthe valve box 53. A slidable valve element 56 is mountedin the valve box chamber so as to uncover alternately the ports 52 and55 and has a cavity or recess which connects the covered portautomatically to an exhaust port 51.

The chamber of the valve box is suppliedwith fluid under pressure, suchas compressed air received through a pipe 58 from an air storage tank59. Thus, as the valve element 56 is reciprocated in the valve box, itwill automatically admit compressed air alternately to the portions ofcylinder 49 on opposite sides of the piston 50, and thus reciprocate thepiston 59 and the valve control rod 48. The `valve element 56 isreciprocated by an operating rod 69 which extends exteriorly' of thevalve box through a suitable packing gland and is operated in a mannerwhich will be described presently. l

To operate the pump reversing rod 3|, the latter extends into a cylinder6| and carries a piston 62. The cylinder 6I is connected, at one side ofthe piston 62 by a pipe 63 to a port 64 opening into the chamber ofanother valve box 65. A pipe 66 connects the cylinder 6| at the oppositeside of the piston 62, to a port 61 which also opens into the chamber ofthe valve box 65. A sliding valve element 68 is provided in the chamberof the valve box 65 to reciprocate back and forth therein and uncoverthe ports 64 and 61 alternately. The valve element 68 has a recess orcavity which automatically connects the covered port 64 or 61 with anexhaust outlet 69 and, thus, by the reciprocation of the valve element68 the pipes 63 and 66 are alternately connected to the exhaust outlet69 and when either of the pipes 63 and 66 is connected to the exhaustoutlet 69, the other pipe is 'uncovered in the chamber of the valve box65.

A pipe 18 connects the pipe 58, supplying compressed air to the valvebox 53, to the chamber of the valve box 65, and thus compressed air willbe admitted alternately to the pipes'63 and 66 in the same manner asexplained for the valve' box 53 which passed compressed air alternatelyinto opposite ends of the cylinder 49. The valve element 68 isreciprocated back and forth by a valve rod 1| which extends exteriorlyof the valve box through a packing gland and may be operated in anydesired manner.

I have found it advantageous to use electrical means for operating thevalve rods 60l and 'Il and this electrical system will now be described.The valve rod 68 is provided at its outer end with an armature 12 ofsoft iron or other magnetically attracted material, and the rod 1I issimilarly provided with an armature or core 13 of similarvmaterial.Springs 14 are connected to the cores or armatures12 and 13 and tend tourge them in directions to pull the valve elements 56 and 68 into thepositions shown in full lines in the drawing. A solenoid 15 is providedfor the armature or' core 12 and, when energized, tends to draw the coreor armature 12 upwardly and shiftl the valve element`56 into theposition shown in dash lines inthe drawing.

Similarly, a solenoid 16 is provided for the core or armature 13, sothat when the solenoid 16 is energized, it will magnetically attract thearmature or core 13, shift it against the action of its spring 14, andmove the valve element 68 into the position shown by dash lines in thedrawing. The solenoid 15 is connected by wires 11 and 18' to contacts 19and 89 respectively of a relay.

A member or arm 8| of the relay carries bridges 82 and 83 thatelectrically connect the contacts 19 and 80 to additional contacts 84and 85, re-

spectively, automatically whenever the relay is energized to shift thearm 8| in one direction against the action of a retracting spring 86.This relay arm is operated, against the action' of the spring 86, tocarry the bridges 82 and 83 into engagement with the contacts 19 and 8|)by means of a solenoid or winding 81 which is connected at one side bywire 88 to a power line wire L1. The other line wireL2 is connected by awire 89, a normally open starting switch 93, and a wire 9| to the otherside of the relay winding 81. Electric current is supplied to thissystem through the line wires L1 and L2 and, thus, when the switch 98 isclosed, current will flow from the line wires` through the relay winding81 to energize it and shift the relay member 8| into circuit closingposition. The relay member 8| also carries a bridge 92 which engages andelectrically connects contacts 93 and 94 whenever the relay winding 81is energized. The contact 93 is connected by wire 95 to one of the linewires, such as L2, and the contact 94 is connected by wire 96, anormally closed switch 91, a wire 98, and a second normally closedswitch 99, to the wire 9| which is connected to the normally open switch98. It will be observed that when the relay Winding 81 is energized andthe bridge 92 connects the contacts or terminals 93 and 94, a circuitwill be established as followsz-from line wire L2, through the wire 95,contact 93, bridge 92, contact 94, wire 96, switch 91, wire 98, switch99, wire 9|, relay winding 81, and wire 88 to the other line wire L1.This circuit last described is what is known as a stick circuit and,when closed, will keep the relay winding 81 energized and thus maintainthe relay member 8| in closed position.

To deenergize the relay winding 81, it is merely necessary to openeither of the switches 91 or 99 of the stick circuit whereupon the relaymember member 8|, and when this occurs, the bridges 82 and 83 willconnect the lines wires L1 and L2 to the wires 11 and 18 which supplycurrentto the winding or solenoid 15. 'I'his winding when energized thenoperates the valve element 56 from the full line position to the dashline position shown on the drawing. Wires |00 and |0| connect the wires11 and 18 to the solenoid or winding 16 of the other valve box, so thatthe two valve rods 60 and 1| will be operated concomitantly under thecontrol of the bridge elements 82 and 83 of the relay. When the -stickcircuit is opened to deenergize the relay winding 81, the windings and16 will be deenergized by the retraction of relay member 8|, and thevalve elements 56 and 68 will be returned to the full line positionsshown in the drawing through the action of the spring 10.

The stick circuit is utilized as a part of a time I control for thepress, .and any suitable means may be employed for opening the stickcircuit, such as by an opening of the switch 91, a predetermined andselected length of time after the relay 81 has been energized which willbe after the platen has been started on its upward movement.' As anexample, I provide a time limit relay |02 whose winding |03 is suppliedwith current to start it into operation by wires |04 and |95 connectingit to the wires 11 and 18 which receive current automatically wheneverthe relay winding 81 is energized. Thus, the winding |03 of the timelimit relay will be energized automatically whenever the relay winding81 is energized. This time limit relay may be of any suitableconstruction, but one form of such a relay is shown in Fig. 2.

This relay shown in Fig. 2 includes the winding |03 which, whenenergized, elevates, by magnetic attraction, a soft iron core |06carrying a piston |01 which reciprocates in a cylinder |08. Air entersbelow the piston |01 through a controlled, adjustable valve |03 untilthe piston |01 uncovers a port I0 in a side wall of the cylinder,whereupon the core |06 may move upwardly freely, and through anextension of the core will engage and open the switch 91 with a rapidmovement. The opening of the stick circuit, through switch 91,deenergizes the relay winding 01 and through it the winding |03 of thetime limit relay and, thereupon, the core |06 falls. or is pulleddownwardly by the springs 2 which are connected to arms I i3 of theextension of the core. A ball check valve ||4 connected to the bottomend of the cylinder |08 allows free escape of air displaced by thedownward movement of the piston |01, but automatically closes to prevententrance of air to the cylinder |08 when the piston |01 startsupwardly.-

In the operation of this system, whenever a pressing movement of theplaten is desired, the attendant closes the switch 90 which completesthe electric circuit through the relay winding 81. Immediately followingthe energization of this winding 81, the member 8| is lifted or moved tocarry the bridge members 82, 83 and 92 into bridging relation with theircoordinated contacts. The bridge member 92 closes the stick circuitwhich keeps the winding 81 energized, and thc bridge members 82 and 83complete the circuit to the time limit relay |02 and to the windings ofsolenoids 15 and 16. The solenoids 15 and '.'6 shift the valve elements56 and 68 from the full to the dotted line positions shown in thedrawing and, in doing so, reverse the delivery of the pump and shift thevalve control rod d6 outwardly into ineffective position,

to the main ram.

When the pump is reversed in this manner, it

-delivers operating fluid into the pipe I8 and thence to the auxiliaryramsv to start the upward movement of the platen, and the suctioncreated by the upward movement of the piston I3 of the main ram drawsoperating fluid from the reser- Voir 2| through the check valve 23 intothe cylinder I4. At the same time that the pump is re. versed and thevalve element 24 released, current begins to ow through the'time limitrelay winding |03. This winding then causes a magnetic attraction andelevation of its core |06 and piston |01, and the upward movement of thepiston |01 of this relay is retarded by the air valve |09. By adjustingthe valve |00, the time required for the piston |01 to reach the port||0 may be varied, and when the piston reaches and uncovers the port||0, it is no longer retarded and moves upwardly at a rapid rate toengage and open the switch 91 which breaks the stick circuit.

Since the starting switch 90 was only operated momentarily in order totemporarily energize the relay winding 81, the opening of the stickcircuit by the time limit relay |02 causes a deenergization of the relaywinding 81, whereupon the circuits which were established by the relay81 will be broken. Thereupon the springs 14 will retract the cores 12and 13 and m'ove the valve elements 56 and 68 from the dash line to fullline positions shown in the drawing. Upon this movement ofI the valveelements 56 and 68, the pump is again reversed so as to draw liquid fromthe auxiliary rams and deliver it to the pipe 20. At the same timepressure is applied to the piston 50 tending to forcethe valve rod 48inwardly. This pressure is at first insuioient to open the valve 24until the pressure in the main ram and pipe 28 has fallen suciently sothat the pressure on the piston 50 can overcome the fluid pressuretransmitted to the valve element 24 from the main ram and the pressureof spring 26. When this occurs the valve element 24 will be forciblyopened so.

that further operating liquid displaced in the main ram cylinder I4 maypass through the valve 23 directly to the reservoir 2| without beinghandled by the pump.

It will be noted that the pump was reversed and a return movement of theplaten started, a selected but adjustable interval of time after thepressing movement of the platen was started, but if the pressure on theplaten reached a selected pressure before this time interval was up,then the pump was automatically set approximately to neutral delivery soas. to maintain that pressure until the time interval expired. l

It will be noted that through the connections which have beenillustrated, the pump operates to transfer the operating liquidv orfluid between the auxiliaryrams and the reservoir alternately, and aftera selected resistance has been encountered by the platen, the pump alsotransfers the operating fluid under pressure from the source Throughythis arrangement, the pump. |1 may be of relatively small capacity, butnevertheless, a Very rapid travel of the platen in both directions ispossible. The auxiliary rams can be made very small so as to operaterapidly with a small capacity pump. 'I'he pressure, in response to whichthe pump automatically sets itself to approximately neutral delivery,may be varied in any suitable manner, such as by adjusting the nuts 35which determine the pressure on lthe spring 34 that must be overcomebefore the pump will change to neutral delivery.

If desired, the valve boxes 53 and 65 and solenoids 'i5 and 16 may bereplaced by a single box and solenoid in which case, the pipes 10 and58, B3 and 54, 66 and 5i will be connected together and to one of thevalve boxes,` and the ,solenoid of the unused valve box may beeliminated.

It will be obvious that various changes in the details, which have beenherein described and illustrated in order to explain the nature of theinvention, may be made by those skilled in the art within the principleand scope of the invention as expressed in the appended claims.

I claim:

l. In a hydraulic press system, a platen, a main ram and a smallerauxiliary ram operable on said platen to force it in a pressingdirection, a source of operating liquid, a pump, connections from saidpump to said source and to said auxiliary ram by which said pump maytransfer operating fluid under pump pressure selectively in eitherdirection between said source and said auxiliary ram, a connection fromsaid source to said main ram, a free check valve in` said last namedconnection and opening freely to pass liquid from said source towardsaid main ram, and automatically closing to prevent return flow, meansincluding a free check valve connected between the connections from thepump to the auxiliary' ram and to the connection from the first freecheck valve to the main ram and opening freely to pass operating liquidfrom the first free check valve to the connection between the auxiliaryram and the pump but closing automatically to prevent reverse flow, apressure opened check valve connected in parallel to said second freecheck valve for preventing fiow in the same direction as the secondcheck valve and automatically opening to pass operating liquid in thereverse direction when the pressure exerted thereon is in excess of aselected value, and means operable to forcibly open said first freecheck valve While the pump is withdrawing liquid from said rams, to passliquid directly from said rams to said source.

2. In a hydraulic vpress system, a platen, a main ram and a smallerauxiliary ram operable on said platen to force it in a pressingdirection, a source of operating liquid, a pump, connections from saidpump to said source and to said auxiliary ram by which said pump maytransfer operating uid in either direction between said source and saidauxiliary ram, a connection from said source to said main rain, a freecheck valve in said last named connection and opening freely to passliquid from said source toward said main ram, and automatically closingto prevent return flow, means including a free check valve connectedbetween the connections from the pump to the auxiliary ram and to theconnection from the first free check valve to the main ram and openingfreely to pass operating liquid from the first free check valve to theconnection between the auxiliary ram and the pump but'closingautomatically to prevent reverse flow, a pressure opened check -valveconnected at one end to the auxiliary ram and at the other end to theconnection receiving fluid from said first free check valve, when thelatter operates as a free check valve, in parallel to said second freecheck valve for preventing flow in the same direction as the secondcheck valve and automatically opening to pass operating liquid in thereverse operating the rst mentioned free check valve into open positionautomatically when the pump and connections are set to-withdrawoperating liquid from said auxiliary rain, whereby operating liquiddisplaced bythe main ram may flowdirectly tosaid source through saidfirst check valve.

3. In a hydraulic press system, a platen, a

main ram and a smaller auxiliary ram for opelating said platen forciblyin one direction, a reversible pump connected at one side to saidauxiliary ram, a source of operating fluid connected to the other sideof said pump, a pipe connecting said source to said main ram, a freecheck valve connected in series in said pipe and freely passing fluidfrom said source'to said main ram and automatically closing to preventreverse iiow, and a pair of check valves connected in parallel at oneside between the portion of the pipe connecting said first check valveand the main ram, and at the other side tc the connection from the pumpto the auxiliary ram one of said Lpair of check valves opening freely topass operating fluid leaving the first free check valve in' thedirection in which it opens freely as a check valve and passing throughsaid pipe to said pump and automatically closing to prevent reverseflow, and the other valve of said pair closing automatically to preventflow in the direction in which it is free to pass in the other valve ofthe pair, but opening to pass said fluidi check vflve connected inseries in said pipe and freely passing fluid from said source to saidmain ram and automatically closing to prevent reverse flow, a pair ofcheck valves connected in parallel at one side between the portion ofthe pipe connecting said first check valve end'the m`in ram, and at theother side to the connection from the pump to the auxiliary ram` one ofseid pair of check valves lopening freely to pass operating fluid fromthe first free check valve and said pipe to said pump and automaticallyclosing to prevent reverse flow, and the other valve of said pairclosing automatically to prevent flow in the direction in which it lefree to pass in the other valve of the pair,V but opening to pass saidfluid in the reverse direction automatical'fy and solely when thcpressure at the side thereof which is connected to the pump and theauxiliary ram exceeds a predetermined pressure, means for reversing thedirection of delivery of said pump, and means external to said hydrauliccircuit but associated with said reversing means for urging the rstmentioned check valve into open position automatically whenever the pumpis s et to withdraw operating fluid from said auxiliary ram.

5. In a hydraulic press system, a platen, a

l main ram and a smaller auxiliary ram operating on said platen to forceit in one direction, a reversible variable delivery pump connected atone side to said auxiliary ram, a source of operating iiuid connected tothe other side of said pump, said pump having means to set'itselfsubstantially to neutral automatically while delivering fluid to saidauxiliary ram Whenever the pressure on said auxiliary ram reaches apredetermined pressure, a pipe connecting said source directly to saidmain ram, a free check valve in series in said pipe and operatingautomaticallyA to pass fiuid freely from s'aid source to said main ramand closing automatically to prevent reverse iiow, and a pair of checkvalves connected, in parallel to one another, to the portion of saidpipe connecting the first check valve to said main ram and to theauxiliary ram, oneof the valves of said pair opening to pass fllrdfreely in a direction from said source through said rst check valve tosaid auxiliary ram and pump, and closing automatically to preventreverse flow, andthe other check valve of the pair operating to pass andrestrict fiow in a manner opposite to the first mentioned valve of thepair, but opening to pass fluid in a direction from said auxiliary ramtoward said first check valve solely when the pressure in the auxiliaryram reaches or exceeds a predetermined pressure, whereby when said pumpis delivering fluid to said auxiliary ram, said fiuid from said pumpwill force the platen upwardly at a rapid rate and the space vacated bythe piston of the main ram will be filled by fiuid passing from saidsource through the first check valve directly to said main ram, and whenthe pressure on said auxiliary ram reaches said predetermined pressure,said pressure-operated check valve will open and pass operating uid fromsaid pump directly to said main ram and cause said first check valve toclose.

6. In aA hydraulic press system,` a platen, a main ram and a smallerauxiliary ram operating on said platen to force it in one direction, areversible variable delivery pump connected at one side to saidauxiliary ram, a source of operating fluid connected to the other sideof said pump, said pump having means to set itself substantially toneutral automatically While delivering fluid to said auxiliary ramwhenever the pressure on said auxiliary ram reaches a. predeterminedpressure, a pipe connecting said source directly to said main ram, afree check valve in series in said pipe and operating automatically topass fiuid freely from said source to said main i ram andr closingautomatically -to prevent reverse fiow, a pair of check valvesconnected, in parallel to one another, to the portion of said pipeconnecting the first check valve to said main ram and to the auxiliaryram, one of the valves of said pair opening to pass fluid freely in adirection from said source through said first check valve to saidauxiliary ram and pump, and closing automatically to prevent reverseflow, and the other check valve of the pair operating to pass andrestrict flow in a manner opposite to the first mentioned valve of thepair, but opening to pass fiuid in a direction from said auxiliary-ramtoward said first check valve solely when the pressure in the auxiliaryram reaches or exceeds a predetermined pressure, whereby when said pumpis delivering fluid to said auxiliary ram, said fluid from said pumpwill force the platen upwardly at a rapid rate and the space vacated bythe piston of the main ram will be filled by fiuid passing from saidsource through the first check `valve directly to said main-ram, andwhen -the pressure on said auxiliary ram reachesV said predeterminedpressure,

said pressure-operated check valve will open and 'pass operating fluidfrom said pump directly to said main ram and cause saidv first checkvalve to close, a control device for reversing the direction of deliveryof said pump, and means for operating said first check valve into openposition whereby when said pump is withdrawing operating fiuid from saidauxiliary ram and returning it to said source, said first check valvemay be opened to permit direct return of fluid displaced by the main ramto said source and continuance of the operation ofl said pump in thesame direction will then draw operating liquid from said source throughthe first check valve and through the first mentioned check valve ofsaid pair, and return it directly to said source.

7. In a hydraulic press system, a platen, a main ram and a smallerauxiliary ram operating on said platen to force it in one direction,

-a reversible variable delivery pump connected at one side to saidauxiliary ram, a source of operating fluid connected to the other sideof said pump, said pump having means to set itto said main ram andclosing automatically to prevent reverse flow, a pair of check valvesconnected, in parallel to one another, to the portion of said pipeconnecting the first check valve to said main ram and to the auxiliaryram, one of the valves of said pair opening to pass fluid freely in a.direction from said source through said first check valve to saidauxiliary ram and pump, and closing automatically to prevent reverseflow, and the other check valve of the pair operating to pass andrestrict flow in a manner opposite to the first mentioned valve of thepair, but opening to pass fluid in a direction from said auxiliary ramtoward said first check valve solely when the pressure in the auxiliaryram reaches or exceeds a predetermined pressure, whereby when said pumpis delivering fluid Ato said auxiliary ram, said fluid from said pumpwill force the platen upwardly at a rapid rate and the space vacated bythe piston of the main ram will be filled by fiuid passing from saidsource through the first check valve directly to said main ram, and whenthe pressure on said auxiliary ram reaches said predetermined pressure,said pressure-operated check valve will open and pass operating fluidfrom said pump directly to said main ram and cause said first checkvalve to close, means for forcibly opening said first check valve, meansfor reversing the direction of delivery of said pump, and common controlmeans for said reversing means and said valve opening means, foroperating the latter to open the rst check valve automatically when thedelivery of the pump is reversed to withdraw operating fluid from saidauxiliary ram.

8. In a hydraulic press system, a platen, a main ram and a smallerauxiliary ram operating on said platen to force it in one direction, areversible variable delivery pump connected at one side to saidauxiliary ram, a source ofoperating fiuid connected to the other side ofsaid pump, said pump having means to set itself substantially to neutralautomatically while delivering fluid to y said auxiliary ram wheneverthe pressure on said auxiliary ram reaches a predetermined pressure, apipe connecting said source directly to said main ram, a free checkvalve in series in said pipe and operating automatically to pass fluid(iii freely from said source to said main ram and closing automaticallyto prevent reverse iiow, a pair of check valves connected, in parallelto one another, to the portion of said pipe connecting the first checkvalve to said main ram and to the auxiliary ram, one of the valves ofsaid pair opening to pass uid freely in a direction from said sourcethrough said first check valve to said auxiliary ram and pump, andclosing automatically to prevent reverse ow, and the other check valveof the pair operating to 'pass and restrict flow in a manner opposite tothe first mentioned valve of the pair, but opening to pass fluid in adirection from said auxiliary ram toward said first check valve solelywhen the pressure in the auxiliary ram reaches or exceeds apredetermined pressure, whereby when said pump is delivering fluid tosaid auxiliary ram, said uid from said pump will force the platenupwardly at a rapid rate and the space vacated by the piston of the mainram Will be filled by fluid passing from said source through the firstcheck valve directly to said main ram, and when the pressure on saidauxiliary ram reaches said predetermined pressure, saidpressure-operated check valve will open and pass operating fluid fromsaid pump directly to said main ram and cause said rst check valve toclose, means for forcibly opening said first check valve, means forreversing the direction of delivery of said pump,l

controlling means for regulating the direction of delivery of said pumpand the activity of the means for forcibly o-pening the rst check valve,means for operating said control means to initiate a pressing movementof said platen, and time controlled means set in motion automatically ateach pressing movement of the platen and operable a predeterminedinterval of time thereafter for reversing the direction of delivery ofsaid pump and opening said rst check valve, whereby the platen mayautomatically return to starting position.

9. In a hydraulic press system, a platen, a main ram and a smallerauxiliary ram connected to said platen for raising said platen in apressing direction, a source of operating fluid connected to said mainram, a free check valve in series in the connection from said source tosaid main ram, yopening to pass uid from said source to said main ram,and closing automatically to prevent reverse ow, means including a pumpconnected to said auxiliary ram'and said source for transferringoperating 'fluid in either direction between them `and forming ahydraulic circuit, valve means for connecting said auxiliary ram to saidmain ram automatically whenever the pressure in the auxiliary ramreaches or exceeds a predetermined pressure, valve means shunting saidpreceding valve means automatically when said pumping means iswithdrawing operating fluid from said auxiliary ram, and means operatingagainst the uid pressure in said hydraulic circuit for forcibly openingsaid first free check valve While said pumping means is withdrawingoperating fluid from the main ram and delivering it to said source.

*10. In a hydraulic press system, a platen, a main ram and a smallerauxiliary ram connected to said platen for raising said platen in apressing direction, a source yof operating fluid connected to said mainram, a free check valve in series in theconnection from said source tosaid main ram, opening to pass fluid from said source to said main ram,and closing automatically to prevent reverse ow, means including a pump0011- nected to said auxiliary ram and said source for transferringoperating fluid in either direction vbetween them, valve means forconnecting said auxiliary ram to said main ram automatically wheneverthe pressure in thekl auxiliary ram reaches or exceeds a predeterminedpressure, valve means shunting said preceding valve means automaticallywhen said pumping means is withdrawing operating fluid from saidauxiliary ram, and means for operating said transferring means to changeits direction of delivery selectively, and automatically opening saidcheck valve while said transferring means is withdrawing fluid from saidauxiliary ram.

11. In a hydraulic press system, a platen, a main ram and a smallerauxiliary ram connected to said platen for raising said platen in apressing direction, a source of operating iiuid connected to said mainram, a free check valve in series in the connection from said source tosaid main ram, opening to pass fluid from said source to said main ram,and closing automatically to prevent reverse ow, means including a pumpconnected to said auxiliary ram and said source for transferringoperating fluid in either direction between them, valve means forconnecting said auxiliary ram to said main ram automatically wheneverthe pressure'in the auxiliary ram reaches or exceeds a predeterminedpressure,.

valve means shunting said preceding valve means automatically when saidpumping means is withdrawing operating fluid from said auxiliary ram,means for operating said transferring means to change its direction ofdelivery selectively, and automatically opening said check valve whilesaid transferring means is withdrawing fluid from said auxiliary ram,and timing means for operating said last preceding means automatically aselected interval of time after said transferring means has been set todeliver operating lfluid to said auxiliary ram.

12. In a hydraulic press system, a platen, a main ram and a smallerauxiliary ram connected to said platen for raising said platen in apressing direction, a source of operating fluid connected to said mainram, a free check valve in series in the connection from said source tosaid main ram,

`opening to pass fluid from said source to said main ram, and closingautomatically to prevent reverse flow, means including a pump connectedto said auxiliary ram and said source for transferring operating fluidin either direction between them, valve means for connecting saidauxiliary ram to said main ram automatically whenever the pressure inthe auxiliary ram reaches or exceeds a predetermined pressure, and valvemeans shunting said preceding valve means automatically when saidpumping means is withdrawing operating fluid from said auxiliary ram,said transferring means .being formed to cease delivery to saidauxiliaryram automatically whenever the pressure on said auxiliary ram reaches aselected maximum.

13. In a hydraulic press system, a platen, a main ram and a smallerauxiliary ram connected to said platen for raising said platen in apressing direction, a source of operating fluid connected` to said mainram, a free check valve in series in the connection from said source tosaid main ram, opening to pass fluid from said Isource to said main ram,and closing automatically to prevent reverse flow, means including apump connected to said auxiliary ram and said source for transferringoperating fluid in either direction between them, valve means forconnecting said auxiliary ram to said main ram automatically wheneverthe pressure in the auxiliary ram reaches or exceeds a predeterminedpressure, valve means shunting said preceding valve means automaticallywhen said pumping means is withdrawing operating fluid from saidauxiliary ram, and means for operating said transferring means to changeits direction of delivery selectively, and automatically opening saidcheck valve while said transferring means is withdrawing fluid from saidauxiliary ram, said transferring means being formed to cease delivery ofsaid operating fluid to said auxiliary ram automatically Whenever thepressure on the auxiliary ram reaches a selected maximum pressure.

14. In a hydraulic press system, a platen, a main ram, and a smallerauxiliary ram connected to said platen for raising it in a pressingdirection, a reservoir for operating fluid, a pipe connecting saidreservoir to said main ram, a free check valve in series in said pipe,normally preventing flow from said main ram to said source and openingfor free ow in the reverse direction,

a reversible, variable "delivery pump connected at one side to saidauxiliary ramand at its other side to said source, and operating to setitself approximately to neutral delivery automatically whenever thepressure .on said auxiliary ram reaches a selected maximum, a pressureopened connection from the side of the pump connected to said auxiliaryram, to said main ram for passing operating uid from the pump to themain cram whenever the pressure on the auxiliary ram reaches or exceedsa selected pressure, and means including a valve connecting said ramsand operable .automatically Ato pass iluid from said main ram to saidauxiliary ram when said pump is withdrawing operating fluid from saidauxiliary ram.

15. In a hydraulic press system, a platen, a main ram and a smallerauxiliary ram connected to said platen for elevating it in a pressingdirection, a source of operating fluid, a reversible pump connected atone side to said auxiliary ram and at its other side to said source, apipe connecting said source to said main ram, valve means connectingsaid rams to pass fluid at any pressure from said main ram to saidauxiliary ram when said pump is withdrawing fluid from said auxiliaryram, and to pass uid from said auxiliary ram to said main ram solelywhen the pressure equals or exceeds a selected maximum pressure, wherebywhen said pump is delivering fluid to said auxiliary ram, said valve insaid pipe may open to pass fluid from said source directly to said mainram until the pressure in said auxiliary ram passes a selected minimumpressure, and whereby said valve in said pipe may be opened to passfluid from said main ram to said source while said pump is withdrawinguid from said auxiliary ram.

16. In a hydraulic press system, a single acting press having a platen,and a main ram and a small auxiliary ram for forcing said platen in onedirection, means including a reversible pump connected to said rams forsupplying an operating -fluid under major pressure to said auxiliaryram,

and an operating fluid under minimum pressure to said main ram whilesaid press is closing against the work, then delivering operating fluidunder major pressure to both of said rams during the remaining pressuremovement. of said platen, and then upon reversal of the pump withdrawingsaid uid from both of said rams, and controlling means for said pump forinitiating a pressing movement of said platen and automaticallyreversing said pump to initiate a return of said platen, a selected andpredetermined interval of time after a pressure movement of said platenhas been initiated.

17. In a hydraulic press system, a single acting press having a platen,and a main ram and a small auxiliary ram for forcing said plateniin onedirection, means including a reversible pump connected to said rams forsupplying an operating fluid under major pressure to said auxiliary ram,and an operating fluid under pressure to said main ram while said pressis closing against the work, then delivering operating uid under majorpressure to both of said rams during the remaining pressure movement ofsaid platen, and then upon reversal of the pump withdrawing said fluidfrom both of said rams, fluid actuated means for reversing the pump, avalve device controlling the operativeness of said reversing means,means including an electric circuit for controlling the operation ofsaid valve device, and a timing device rendered operative by saidcircuit when said circuit is rendered effective to cause delivery of thepump in one direction, for automatically causing the reversal of thepump a predetermined interval of time thereafter.

18. In a hydraulic press system, a platen, a main ram and a smallerauxiliary ram connected to said platen for raising said platen in apressing direction, a source of operating fluid connected to said mainram, a free check valve in series in the connection from said source tosaid main ram, opening to pass uid from said source to said main ram,and closing automatically to prevent reverse flow, means including apump connected to said auxiliary ram and said source for transferringoperating fluid in either direction between them, valve means forconnecting said auxiliary ram to said main ram automatically wheneverthe pressure in the auxiliary ram reaches or exceeds a predeterminedpressure, valve means shunting said preceding valve means automaticallywhen said pumping means is withdrawing operating uid from said auxiliaryram, uid operated means for actuating said transferring means to changeits direction of delivery selectively, fluid operated means forautomatically opening said check valve, valve devices for controllingboth of said fluid -operated means, and means including an electriccircuit for controlling the activity of said valve devices so as tocause said check valve to open automatically when the delivery of saidtransferring means is changed so as to Withdraw the operating fluid fromsaid rams.

19. In a hydraulic press system, a platen, a

'main ram and a smaller auxiliary ram connected to said platen forraising said platen in a pressing direction, a source of operating fluidconnected to said main ram, a free check valve in series in theconnection from said source to said main ram, opening to pass fluid fromsaid source to lsaid main ram, and closing automatically to preferringmeans to change its direction of delivery selectively, fluid operatedmeans for automatically opening said check valve, valve devices forcontrolling both of said uid operated means, means including an electriccircuit for controlling the activity of said valve devices so as tocause said check valve to open automatically when the delivery of saidtransferring means is changed so as to withdraw the operating uid fromsaid rams, and timing means automatically 'set in operation by anoperation of said circuit to initiate a forced movement of said rams,and causing an actuation of said valve devices to initiate a withdrawalof fluid from said rams, a predetermined interval of time after saidtransferring means has been actuated to initiate said forced movement ofsaid rams.

THOMAS F. STACY.

